Ganged rotary variable resistor assembly



E L 0,4 N ///l 1 k 4) N \I V April 5, 1966 c. R. GOERG 3,245,022

GANGED ROTARY VARIABLE RESISTOR ASSEMBLY Filed April 11, 1963 INVENTOR CHAR S R 6 5% ATTORNEY 3,245,022 GANGED ROTARY VARIABLE RESISTOR ASSEMBLY Charles R. Goerg. Milwaukee, Wis, assignor to Globe- Union, Inc., Milwaukee, Wis, a corporation of Dela- Ware Y Filed Apr. 11, .1963, Ser. No. 272,366

. 3 Claims- (Cl. 338-132) This invention pertains to variable electrical control 'units and in particular to improve means for assembling ,and retaining separate units inv stacked assemblies.

Stacked assemblies in essence consist of .a number of electrical control units, such as rotary switches or potentiometers, which are coaxially aligned and secured to each other, and are adapted for simultaneous actuation in response to rotation of a control shaft. The electrical control units are manufactured and carried by dealers as separate items and are used either separately, or more frequently, in stacks of two or more units, the number of units per stack depending upon the particular application and/ or design. To provide this versatility, the control junits have to be designed to permit their interconnection in a manner which permits the simultaneous transfer of the rotary motion of the control shaft to all of the units of the stack regardless of the particular number of units per stack.

One approach has been to employ a single centrally I disposed shaf-tto engage the rotary contactor or resistor of each control unit of the stack and to thus permit simultaneous actuation of all the units. Of course, in this case the length of the shaft varieswith the number of units per stack, thus forcing the manufacturerto producesuch shafts of various lengths, and the user to decide upon the number of units per stack at the time of his purchase.

A second approach has been to provide the rotors with tongue and groove means located on the sides of mating faces of each unit, which means are adapted to mate when the units are interconnected. In this case the assembly of tween each adjacent unit, which lag becomes seriously objectionable when multiplied by the number of units in one stack.

The principal object of this invention is to provide 'variable electrical control units which are more easily assembled in stacked relationship and which are more accurately actuated than similar units known heretofore.

This object is attained by control units which have their rotors secured to relatively short central shafts,

and by coupling means forconnecting the shafts of adjacent units when they are stacked which do not have the heretofore objectionableclearance requirements and which lend themselves to blind assembly." The coupling means comprises an extension of the shaft shaped to provide two opposing fiat faces and a female member having two jaws which are adapted to engage the fiat faces of the shaft of an adjacent unit when the units are assembled in a stacked relationship. The distance between opposing jaws is slightly smaller than the distance between the opposing faces of the shaft extension, thus requiring the jaws to be forced apart when the shaft extension is inserted between them. It is apparent that by this method of coupling, the jaws grip the shaft and are biased in contact therewith, thus avoiding anyof the heretofore required clearances. The jaws, although being resilient, are suffi-ciently stiff so as not to deform or give when the shaft is rotated in actuation of the unit.

United States Patent O cirmped to engage .a groove 27 in the with .a housing with two opposing flat adapted to be engaged Further, the front ends of the jaws are tapered outwardly to create a funnel effect and thus permit coupling of the units in a blind assembly wherein the jaws will seek the as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawing in which:

FIG. 1 is a cross sectional view in side elevation of a stacked control assembly of three control units embodying the present invention;

FIG. 2 is a fragmentary view in the side elevation, with part broken away and shown in section, of the coupling means in a disengaged position;

FIG. 3 is a view taken along line 3-3 of FIG. 1 withpart broken away and shown in section; and

FIG. 4 is a view in the top elevation of the coupling 1 means in an engaged position.

Referring'to the drawing in detail, FIG. 1 shows a stacked control assembly of three potentiometer units 10, each having a base 12 and a rotor 14 which is fixed to a central shaft 16 and adapted to sweep a'brush 18 across a resistance track 20 upon rotation of the shaft. The housings 22 of the left hand and center otentiometers in FIG, 1 are fixed to the face portion 28 of the next Successive unit by flange 24 of the bushing 26 which is in turn secured to the shaft 16 of such unit by retainer rings In a stacked assembly the units are secured against rotational and longitudinal movement in respect to each other by means of tabs 25 which in assembly are base and by the housing 22 which engages the face portion of the next successive unit.

The left hand unit of the assembly has a mounting bushing,32 differing from the bushings 26 only by having an extended threaded portion 33 by means of which the assembly is mounted on a panel (not shown) or other sup port member. The last unit of the assembly is provided 35 that completely encloses the control elements .of the potentiometer and'is affixed to its base I 12 by means of tabs.

The essence of the invention lies in the means provided for coupling the shafts 16 of adjacent unit so as to provide both easy assembly and accurate simultaneous actuation of all rotors of the stacked control assembly. To accomplish this, each shaft (with exception of the first unit) is extended beyond the'rear wall 28 of the uni-t and provided faces 34, 34 each of which is by one of two jaws 36, 36 of. a generally U-shaped female member 38 of the adjoining unit. A female member is fixed to a reduced end portion of each shaft 16 (with exception of the last unit) by means of swaged shaft end 40 and is secured against rotation in respect thereto by means of radial projections 42. As shown in the drawings, the reduced end portion of the shaft 16 forms an annular shoulder on the shaft which functions as an abutment against which the rotor 14 and the female member 38 are confined by said swaged shaft end 40.

As illustrated in FIG. 2, the jaws 36, 36, when disengaged from the faces 34, 34, as prior to the assembly of the units, are a smaller distance apart from each other than the distance between faces 34, 34. The jaws are sufficiently resilient to spread apart when the shaft 16 is pushed between them, and upon doing so, exert a substantial gripping force against the faces of the shaft. The bias of the jaws against the faces 34, 34 creates a positive and continuous lineal contact on both opposing faces of the shaft and eliminates any of the looseness and clearances between the mating parts as heretofore required when using tongue and groove means. By means of this positive connection the back lash problem in stacked assemblieshas been eliminated.

It is also of note that the effectiveness of the coupling means is not dependent upon axial dimensional accuracy, and that therefore the shaft 16 may be extended sufficient- 1y far beyond the rear wall 28 to compensate for any axial dimensional variances in the housing or other components.

The ease in assembly of the units in a stacked relationship is facilitated by providing the jaws 36 with outwardly tapered ends 44 which during assembly tend to seek and align the shaft 16 in the proper position. In this respect the assembly is further simplified by providing a slight taper 46 to the end of shaft 16.

As illustrated in FIG. 1, the shaft 16 of the first unit need not be provided with the two heretofore mentioned opposite faces, but may be extended through the bushing 32 to serve as the control shaft by means of which all the separate units of the stack can be simultaneously actuated. Forthis purpose the shaft may be provided with a knob or the like (not shown).

Although this invention has been disclosed as applied to stacked potentiometer units, it is not intended to be limited to this type of electrical controls, but, as should be apparent to those skilled in this art, is equally well applicable to any type of electrical control which is adapted to be assembled in a stacked relationship with other controls and to be simultaneously actuated with such other units in response to rotary motion of a control shaft.

I claim:

1. A gang of rotary variable resistors comprising at least two variable resistor units, each unit comprisinga casing element and a shaft element rotatively supported within the casing element, a resistance member carried by said casing element, a rotor member mounted on said shaft and carrying a contact member engaging said resistance member for traversing said resistance member on relative rotation of said shaft and casing, and means on the ends of the shaft elements of said units for axially coupling two immediately adjacent shaft members for back-lash-free rotational movement in unison comprising an axial extension on one of said shaft elements of reduced diameter to form an annular shoulder on said shaft, said rotor member being mounted on said shaft extension in abutting relation to said shoulder, a U-shaped spring clip member mounted on said shaft extension between the rotor and the end of the shaft extension, and means securing said rotor and spring clip member on said shaft extension so as to be fixed against rotation with respect thereto and against axial movement with respect to said shoulder, said spring clip including a pair of spaced apart spring arms terminating in outwardly flared portions, and a pair of flat surface portions on the adjacent end of the other shaft element, said flat surface portions being spaced apart a distance greater than the normal distance between said spring arms, said adjacent end portion of said other shaft element being substantially coaxially aligned with said one shaft element and disposed between and engaged with the arms of the spring clip carried by said one shaft element with the spring arms of said clip frictionally engaging the flat surface portions of said other shaft element, thereby coaxially coupling the shafts of said units for back-lash-free rotation in unison.

2. A rotary variable resistor unit adapted to be ganged with mating variable resistor units for unison rotational adjustment, comprising a casing element, a shaft element supported in said casing element for rotation, a resistance member carried by one of said elements, a rotor member carried by the other of said elements, said rotor member including a contactor traversing said resistance member on relative rotation of said elements, first shaft coupling means comprising a pair of flat surface portions on opposite sides of said shaft element at one end thereof, an axial shaft extension of reduced diameter at the other end of the shaft forming an annular shoulder on said shaft, said rotor member being mounted on said shaft extension in abutting relation to said shoulder, second shaft coupling means on said other end of the shaft comprising a U-shaped spring clip member mounted on said shaft extension with the spring arms thereof extending axially of the shaft and terminating in outwardly flared end portions adapted to engage the fiat surface portions of the first coupling means on the shaft of an adjacent variable resistor unit when ganged, and means for securing the rotor member and said clip member on said shaft extension so as to be fixed against rotational movement with respect to the shaft and against axial movement with respect to said shoulder, said fiat surface portions being spaced apart a distance greater than the normal distance between said spring arms, whereby the shafts of a plurality of variable resistor units can be coaxially coupled for back-lash-free rotational movement in unison.

3. The variable resistor unit described in claim 2 wherein said means for securing the rotor member and U-shaped clip to said shaft extension comprises a portion of said shaft extension swaged over to form an annular shoulder confining said rotor and clip member against axial movement with respect to said shoulder and radial projections on said shaft extension interengaged with said rotor and said spring clip for securing said rotor and spring clip against rotation relative to the shaft.

References Cited by the Examiner UNITED STATES PATENTS 1,466,293 8/1923 Brooks 338-132 2,143,401 1/1939 Arvin 644 2,434,248 1/1948 Mucher 338132 X 2,525,993 10/1950 Youngbeck et al. 338-132 2,688,857 9/1954 Jones 644 X 2,852,644 9/1958 Elliott 338-132 X 2,861,437 11/1958 Bachman 6415 2,971,174 2/1961 Lyon 338-430 3,027,530 3/1962 Shea 338 RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner. 

1. A GANG OF ROTARY VARIABLE RESISTORS COMPRISING AT LEAST TWO VARIABLE RESISTOR UNITS, EACH UNIT COMPRISING A CASING ELEMENT AND A SHAFT ELEMENT ROTATIVELY SUPPORTED WITHIN THE CASING ELEMENT, A RESISTANCE MEMBER CARRIED BY SAID CASING ELEMENT, A ROTOR MEMBER MOUNTED ON SAID SHAFT AND CARRYING A CONTACT MEMBER ENGAGING SAID RESISTANCE MEMBER FOR TRAVERSING SAID RESISTASNCCE MEMBER ON RELATIVE ROTATION OF SAID SHAFT AND CASING, AND MEANS ON THE ENDS OF THE SHAFT ELEMENTS OF SAID UNITS FOR AXIALLY COUPLING TWO IMMDEIATELY ADJACENT SHAFT MEMBERS FOR BACK-LASH-FREE ROTATIONAL MOVEMENT IN UNISON COMPRISING AN AXIAL EXTENSION ON ONE OF SAID SHAFT ELEMENTS OF REDUCED DIAMETER TO FORM AN ANNULAR SHOULDER ON SAID SHAFT, SAID ROTOR MEMBER BING MOUNTED ON SAID SHAFT EXTENSION IN ABUTTING RELATION TO SAID SHOULDER, A U-SHAPED SPRING CLIP MEMBER MOUNTED ON SAID SHAFT EXTENSION BETWEEN THE ROTOR AND THE END OF THE SHAFT EXTENSION, AND MEANS SECURING SAID ROTOR AND SPRING CLIP MEMBER ON SAID SHAFT EXTENSION SO AS TO BE FIXED AGAINST ROTATION WITH RESPECT THERETO AND AGAINST AXIAL MOVEMENT WITH RESPECT TO SAID SHOULDER, SAID SPRING CLIP INCLUDING A PAIR OF SPACED APART SPRING ARMS TERMINATING IN OUTWARDLY FLARED PORTIONS, AND A PAIR OF FLAT SURFACE PORTIONS ON THE ADJACENT END OF THE OTHER SHAFT ELEMENT, SAID FLAT SURFACE PORTIONS BEING SPACED APART A DISTANCE GREATER THAN THE NORMAL DISTANCE BETWEEN SAID SPRING ARMS, SAID ADJACENT END PORTION OF SAID OTHER SHAFT ELEMENT BEING SUSBTANTIALLY COAXIALLY ALIGNED WITH SAID ONE SHAFT ELEMENT AND DISPOSED BETWEEN AND ENGAGED WITH THE ARMS OF THE SPRING CLIP CARRIED BY SAID ONE SHAFT ELEMENT WITH THE SPRING ARMS OF SAID CLIP FRICTIONALLY ENGAGING THE FLAT SURFACE PORTIONS OF SAID OTHER SHAFT ELEMENT, THEREBY COAXIALLY COUPLING THE SHAFTS OF SAID UNITS FOR BACK-LASH-FREE ROTATION IN UNISON. 